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A receding contact problem between a graded piezoelectric layer and a piezoelectric substrate

ARCHIVE OF APPLIED MECHANICS 2021年第12期91卷 4835-4854页

作者： El-Borgi, Sami Comez, Isa Guler, Mehmet Ali Texas A&M Univ Qatar Mech Engn Program Engn BldgPOB 23874 Doha Qatar Karadeniz Tech Univ Dept Civil Engn TR-61080 Ortahisar Trabzon Turkey Amer Univ Middle East Coll Engn & Technol Egaila Kuwait

The receding contact problem between a graded piezoelectric layer and a homogeneous piezoelectric substrate is considered in this paper. It is assumed that the gradation of the elastic piezoelectric graded layer is of exponential type through its thickness. Using standard Fourier transform, the contact problem is converted to a system of two singular integral equations in which the contact pressures and the electric charge displacement in addition to the contact dimensions are the unknowns. The integral equations are then solved numerically using Gauss-Jacobi integration formula. The primary objective of this paper is to investigate the effect of material gradation on the contact pressure, electric charge distribution and on the length of the receding contact. The main findings of the paper are that the inhomogeneity parameter has a strong effect on the contact pressure and the electric charge distribution at the receding contact interface. It is concluded that a softer FGPM in +z direction results in lower contact pressure and electric displacement.

关键词： Functionally graded piezoelectric material Plane receding contact Singular integral equations Gauss-Chebyshev quadrature collocation iterative algorithm

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Multi-Objective Optimization Strategy of Integrated Electric-Heat System Based on Energy Storage Situation Division

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IEEE ACCESS 2021年 9卷 19004-19024页

作者： Liu, Xinrui Zhang, Fujia Sun, Qiuye Zhong, Weiyang Northeastern Univ Coll Informat Sci & Engn Shenyang 110819 Peoples R China

There are the transmission loss of the electric power network, the delay and loss of the heating network, the insufficient utilization of flexible resources such as energy storage in the integrated electric-heat system, which may lead to the imbalance of supply and demand and energy waste. In this paper, the coordinated dispatch of integrated electric-heat system (IEHS) considering the transmission characteristics of the electric power network and heating network, which is formulated as a convex quadratic program. The strong linkage of electric power and heat supplies can be decoupled to reduce wind power curtailment by exploiting the energy storage and regulation capabilities of the district heating network (DHN), storage batteries, electric boilers (EBs) and heat storage tanks (HSs). The energy storage system works according to the situation division strategy designed in this paper. This paper introduces the wind curtailment boundary power and optimizes dispatch based on the wind curtailment boundary power and unit output, which can make full use of the energy storage capacity and reduce the wind abandonment power. Since the electric power system (EPS) and the distribution heating system (DHS) are controlled separately by different operation organizations, IEHS is solved using double-lambda iterative algorithm. The double-lambda iterative algorithm, with guaranteed convergence for convex programs, can achieve a fully distributed solution for the IEHS and requires only a small amount boundary information exchange between the EPS and the DHS. At last, one integrated electric-heat system was studied to demonstrate the effectiveness of the proposed method which achieves the effective solution in a moderate number of iterations. This system includes two 10-nodes heating system and one 14-nodes electric power system.

关键词： Integrated electric-heat system energy storage situation network transmission characteristics wind power accommodation double-lambda iterative algorithm

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Comparison of Deterministic Methods to Estimate Sidereal Rotation Period from Light Curves

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JOURNAL OF SPACECRAFT AND ROCKETS 2021年第6期58卷 1733-1751页

作者： Balachandran, Katiyayni Subbarao, Kamesh Univ Texas Arlington Dept Mech & Aerosp Engn Arlington TX 76019 USA

The importance of determining the sidereal rotation period of an astronomical object on future investigations pertaining to said object has been well documented in the literature. Researchers, however, have differed in their techniques used to estimate and model objects in the space catalog. In this paper, several period-estimation methods will be explored ranging across Fourier and phase-folding techniques. These methods will be tested using ground-based observations of light curve data for various resident space objects that fall under a rigid body context (i.e., asteroids, satellites, probes, rocket bodies) and celestial objects like stars and extrasolar planets. The effect of varying sample size, the inadequacies in unevenly sampled data processing, autonomy of the method, and complexity of parameters are investigated. For the models of artificial space objects that are not open source, a simulation is used to generate synthetic light curves with which all of the above-mentioned techniques are also employed. To account for heterogeneity in method parameters, each technique is tested with a range of values to optimize the rotational period. Results for uniformly sampled asteroid data as well as nonuniformly sampled stellar objects and generic sinusoidal data show variances in accuracy of the methods, but certain methods stand out.

关键词： Asteroids Geosynchronous Satellite Rockets Earth Resident Space Object Data Processing Power Spectral Density Regolith Advanced Surface Systems Operations Robot Phase Diagram iterative algorithm

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Joint Time and Power Allocation for 5G NR Unlicensed Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2021年第9期20卷 6195-6209页

作者： Bao, Haizhou Huo, Yiming Dong, Xiaodai Huang, Chuanhe Wuhan Univ Sch Comp Sci Wuhan 430072 Peoples R China Univ Victoria Dept Elect & Comp Engn Victoria BC V8P 5C2 Canada

The fifth-generation (5G) and beyond networks are designed to efficiently utilize the spectrum resources to meet various quality of service (QoS) requirements. The unlicensed frequency bands used by WiFi are mainly deployed for indoor applications and are not always fully occupied. The cellular industry has been working to enable cellular and WiFi coexistence. In particular, 5G New Radio in unlicensed channel spectrum (NR-U) supports the uplink and downlink transmission on the maximum channel occupation time (MCOT) duration. In this paper, we consider maximizing the total throughput of both downlink and uplink in NR-U by jointly optimizing the time and power allocation during MCOT while ensuring fair coexistence with WiFi. Fairness is guaranteed in two steps: 1) tuning the access related parameters of NR-U to achieve proportional fairness, and 2) including 3GPP fairness from the throughput perspective as a constraint in NR-U throughput maximization. Numerical analysis and simulation have demonstrated the superior performance of the proposed resource allocation algorithm compared to conventional deployment strategies.

关键词： Wireless fidelity Throughput Long Term Evolution 3GPP Resource management 5G mobile communication Uplink 5G NR-U spectrum sharing resource management cellular WiFi iterative algorithm

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Separation of Overlapping Spectral Lines Using the Tikhonov Regularization Method

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JOURNAL OF APPLIED SPECTROSCOPY 2021年第2期88卷 373-381页

作者： Nemtsova, O. M. Konygin, G. N. Porsev, V. E. Russian Acad Sci Udmurt Fed Res Ctr Ural Branch Izhevsk 426067 Russia

An algorithm for separating overlapping spectral components using the Tikhonov weighted regularization method is proposed. Use of the weighting function allows one to significantly reduce the regularization parameters and separate closely spaced spectral lines. The problem of the appearance of spurious oscillations in a sparse solution is solved by an iterative algorithm for correcting the main matrix. An a posteriori minimum threshold algorithm is used to determine the regularization parameter that provides the maximum resolution of the method. Use of the algorithm fundamentally improves the quality of spectra processing and increases the information content of the spectroscopic methods. The efficiency of the proposed algorithm is shown using processing of model and experimental Mossbauer spectra as examples.

关键词： Mossbauer spectroscopy Fredholm integral equation of the 1st kind weighted regularization iterative algorithm

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Dynamic solution for vehicle-track interaction considering the elastoplasticity of track slabs

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JOURNAL OF VIBRATION AND CONTROL 2021年第13-14期27卷 1668-1680页

作者： Xu, Lei Yu, Zhiwu Cent South Univ Sch Civil Engn Dept Railway Engn 22 Shaoshan Rd Changsha 410083 Peoples R China

In this work, an entire multi-rigid-body system with two-stage suspension systems is assumed to run on a slab track system, where the elastoplasticity of the track slab is modeled by Mindlin plate theory considered in a framework of three-dimensional vehicle-track dynamic system. Considering the elastoplasticity of track slabs, the nonlinearity and time- and stress-dependent track slab stiffness matrices must be accounted for in the time-domain dynamic solutions;therefore, a two-step iterative algorithm separating the vehicle-track system into vehicle-rail subsystem and track slab system is developed to solve the dynamic equations of motion for vehicle-track interactions. The numerical studies have shown the accuracy and efficiency of this method in calibrating the vehicle-track dynamic behavior in conditions of track slab elastoplastic deformation. Besides, it has shown that the longitudinal unevenness of the track support stiffness has significant influence on the plasticity of track slabs.

关键词： Vehicle-track interaction elastoplastic dynamics Mindlin plate theory iterative algorithm plastic deformation

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Analysis on the stiffness iteration of segmental joints in segmental linings: Method and sensitivity analysis

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TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 2021年 115卷 104043-104043页

作者： Feng, Kun Zhang, Li Guo, Wenqi Yang, Renjie He, Chuan Zhang, Jingxuan Southwest Jiaotong Univ Key Lab Transportat Tunnel Engn Minist Educ Chengdu 610031 Peoples R China Southwest Jiaotong Univ China Japan RSC Struct Res Ctr Chengdu 610031 Peoples R China

In current structural analyses on segmental linings, the bending stiffness of segmental joints is usually treated as a constant, which results in a deviation in the calculated internal forces and deformation. In view of this, a finite element model of segmental linings is established using one ring and two half rings. An iterative algorithm is designed with a 3D curved surface of bending stiffness for the segmental joint, obtained from a series of full-scale tests under different axial force and bending moment cases. The rational convergence criteria for the iterative algorithm are recommended by evaluating the convergence efficiency of the iterative algorithm. Moreover, the influence of load magnitude and initial value of bending stiffness, as well as the changing laws of structural internal forces and deformation with the assembly angles, are presented and analyzed. The results show that with the same load, the convergence of the iterative algorithm in staggered-jointed assembly structures (STGS) is better than that of straight-jointed assembly structures (STRS), owing to its greater overall stiffness. The initial input value of bending stiffness has no effect on the convergence of the proposed iterative algorithm, and generally the convergence performance in STGS is better than that in STRS. In STRS, the bending moment is most sensitive to the changes of assembly angles, while in STGS the assembly angles have great influence on both the bending moment and structural displacement. Without the stiffness iteration, the maximum differences for maximum axial force, bending moment, and displacement under different assembly angle in STRS are 11.7%, 31.9% and 22.3%, respectively, and that differences in STGS are 10.4%, 59.3% and 35.1%, respectively. With the stiffness iterative method, the increase amplitude of the maximum axial force, the maximum bending moment, and the maximum displacement in STRS and STGS are 50.0%, 317.4%, 77.1% and 41.9%, 459.3%, 156.5%, respectivel

关键词： Shield tunnel Segmental joint Bending stiffness iterative algorithm Convergence performance

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A Riccati-type algorithm for solving generalized Hermitian eigenvalue problems

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JOURNAL OF SUPERCOMPUTING 2021年第2期77卷 2091-2102页

作者： Miyata, Takafumi Fukuoka Inst Technol Dept Comp Sci & Engn Higashi Ku 3-30-1 Wajiro Higashi Fukuoka 8110295 Japan

The paper describes a heuristic algorithm for solving a generalized Hermitian eigenvalue problem fast. The algorithm searches a subspace for an approximate solution of the problem. If the approximate solution is unacceptable, the subspace is expanded to a larger one, and then, in the expanded subspace a possibly better approximated solution is computed. The algorithm iterates these two steps alternately. Thus, the speed of the convergence of the algorithm depends on how to generate a subspace. In this paper, we derive a Riccati equation whose solution can correct the approximate solution of a generalized Hermitian eigenvalue problem to the exact one. In other words, the solution of the eigenvalue problem can be found if a subspace is expanded by the solution of the Riccati equation. This is a feature the existing algorithms such as the Krylov subspace algorithm implemented in the MATLAB and the Jacobi-Davidson algorithm do not have. However, similar to solving the eigenvalue problem, solving the Riccati equation is time-consuming. We consider solving the Riccati equation with low accuracy and use its approximate solution to expand a subspace. The implementation of this heuristic algorithm is discussed so that the computational cost of the algorithm can be saved. Some experimental results show that the heuristic algorithm converges within fewer iterations and thus requires lesser computational time comparing with the existing algorithms.

关键词： Generalized Hermitian eigenvalue problem Riccati equation Orthogonal component correction iterative algorithm

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Intelligent interference cancellation and ambient backscatter signal extraction for wireless-powered UAV IoT network

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EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2024年第1期2024卷 30页

作者： Zhong, Cheng Zhai, Di Lu, Yang Li, Ke State Grid Xiongan New Area Elect Power Supply Co Baoding 0710002 Heibei Peoples R China State Grid Smart Grid Res Inst Co Ltd Beijing 102209 Peoples R China Univ Sci & Technol Beijing 30 Xueyuan Rd Beijing 100083 Peoples R China

Unmanned aerial vehicles (UAVs) offer a new approach to wireless communication, leveraging their high mobility, flexibility, and visual communication capabilities. Ambient backscatter communication enables Internet of Things devices to transmit data by reflecting and modulating ambient radio waves, eliminating the need for additional wireless channels, and reducing energy consumption and cost for sensors. However, passive ambient backscatter communication has limitations such as limited range and poor communication quality. By utilizing UAVs as communication nodes, these limitations can be overcome, expanding the communication range and improving the quality of communication. Although some research has been conducted on combining UAVs and ambient backscatter, several challenges remain. One key challenge is the strong direct link interference in ambient backscatter under UAV conditions, which significantly affects communication quality. In this paper, we propose an intelligent backward and forward straight link interference cancellation algorithm based on NOMA decoding technique to enhance ambient backscatter communication quality under UAV conditions and extract more ambient energy for UAV energy supply. The paper includes theoretical derivation, algorithm description, and simulation analysis to validate the error bit rate of labeled information bits. The results demonstrate that the forward algorithm reduces the error bit rate by approximately 20% under low signal-to-noise ratio (SNR) conditions, while the backward algorithm reduces the error bit rate under high SNR conditions. The combination of the forward and backward algorithms reduces the error bit rate under both high and low SNR conditions. The proposed method contributes to improving the quality of ambient backscatter communication in UAV settings.

关键词： Unmanned aerial vehicle Ambient backscatter iterative algorithm Energy harvesting

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Estimation of population column proportions of 1's in survey type designs

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COMMUNICATIONS IN STATISTICS-THEORY AND METHODS 2021年第23期50卷 5554-5560页

作者： Kim, Sungsu Univ Louisiana Lafayette Dept Math Lafayette LA 70504 USA

Motivated by the nature of observed responses in real world situations, we propose an iterative algorithm for estimating population column proportions of a n x k Bernoulli random matrix (X) in survey type designs. The Perron-Frobenius theorem is used to establish the limiting form of the proposed estimator in the iteration process, where p(j), j=1, ..., k, is given by the row sum of the Perron projection of X-tX or X-t (1(n) X). An asymptotic distribution of the proposed estimator is provided in this paper.

关键词： Bernoulli random matrix eigenvalue and eigenvector factor analysis iterative algorithm Perron-Frobenius theorem survey design

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